Ozone is a substance having a very strong oxidizability, and water in which ozone is dissolved, so-called ozone water is expected to be utilized in a broad region of cleaning and sterilizing, such as sterilizing of water and sewage or food, and cleaning in a process of manufacturing a semiconductor device. As a method of generating the ozone water, there is known a method of dissolving in water the ozone generated by ultraviolet irradiation or electric discharge, or a method of generating the ozone in water by electrolysis of water.
In Japanese Patent Application Laid-Open No. 11-77060, there is described an ozone water generation device comprising: ozone generating means for generating an ozone gas by an ultraviolet lamp; and a water storage tank. When the generated ozone gas is supplied to the water in the tank, the ozone water is generated. In Japanese Patent Application Laid-Open No. 11-333475, there is described an ozone water generation device which mixes the ozone gas generated by an electric discharge type ozone gas generating device with the water at a predetermined ratio by a mixing pump in order to dissolve the ozone gas in the water with a good efficiency.
However, in the ozone water generating method of generating the ozone gas by the ultraviolet lamp or the electric discharge system as described above to dissolve the ozone gas in the water, there is required the ozone gas generating device or an operation for dissolving the ozone gas in the water, and the apparatus is easily complicated. In the method, since the generated ozone gas is dissolved in the water, there has been a problem that it is difficult to generate the ozone water having a desired concentration with a high efficiency.
In Japanese Patent Application Laid-Open No. 2002-80986, as a method which solves the above-described problem, there is described a method of generating the ozone in the water by the electrolysis of the water to obtain the ozone water. There are described an electrode for ozone generation comprising: an electrode base material constituted of a porous material or a net-like material; and an electrode catalyst containing an oxide of a platinum group element or the like, and ozone water manufacturing method and apparatus using this electrode for ozone generation.
The platinum group element is a standard anode material, and has a characteristic that the element is hardly dissolved in an aqueous solution which does not contain any organic material, but the element has an ozone generation efficiency which is insufficient for the electrode for ozone generation, and it is difficult to generate the ozone water by a high-efficiency electrolysis process. In the ozone water generation by the electrolysis process using such conventional electrode for ozone generation, the electrolysis at a high current density is required for the ozone generation, and there is a problem in energy consumption or electrode life.
An object of the present invention is to provide an electrode for electrolysis which is preferable in generation by an electrolysis process for ozone water usable in cleaning and sterilizing of water and sewage or food or cleaning in a process of manufacturing a semiconductor device, and a method of manufacturing the electrode for electrolysis.